Update packages.mk
Update packages.mk

Minor change to packages makefile for zlib
unobtanium-official/Unobtanium,unobtanium-official/Unobtanium,unobtanium-official/Unobtanium,unobtanium-official/Unobtanium,unobtanium-official/Unobtanium,unobtanium-official/Unobtanium